This invention relates generally to an electrostatographic copier or printer, and more particularly, concerns a cleaning apparatus.
In an electrophotographic application such as xerography, a charge retentive surface (i.e., photoconductor, photoreceptor or imaging surface) is electrostatically charged, and exposed to a light pattern of an original image to be reproduced to selectively discharge the surface in accordance therewith. The resulting pattern 0f charged and discharged areas on that surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable powder referred to as "toner". Toner is held on the image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate (e.g., paper), and the image affixed thereto to form a permanent record of the image to be reproduced. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. The process is well known, and useful for light lens copying from an original, and printing applications from electronically generated or stored originals, where a charge surface may be imagewise discharged in a variety of ways. Ion projection devices where a charge is imagewise deposited on a charge retentive substrate operates similarly.
Although a preponderance of the toner forming the image is transferred to the paper during transfer, some toner invariably remains on the charge retentive surface, it being held thereto by relatively high electrostatic and/or mechanical forces. Additionally, paper fibers, Kaolin and other debris have a tendency to be attracted to the charge retentive surface. It is essential for optimum operation that the toner remaining on the surface be cleaned thoroughly therefrom.
Conventional cleaning methods for cleaning this residual toner include contact cleaners (i.e. cleaners that frictionally contact the imaging surface) such as blades and brushes. The contact between these cleaners and the surface being cleaned, decrease the wear life of both the cleaner and the photoreceptor. This frictional contact can cause tearing and chipping to the cleaning blade edge which leads to cleaning failures and possible damage to the photoreceptor. The cleaning brushes often develop a set due to contact with the imaging surface, that affects the ability of the brush to clean the surface.
The following disclosures may be relevant to various aspects of the present invention and may be briefly summarized as follows:
U.S. Pat. No. 3,257,224 to Jous et al. which discloses a magnetic roller that dips into developer powder contained in a trough beneath the roller. The iron filings, carrying the toner on their surfaces, adhere in brush-like formation to the magnetic poles of the roller and are applied in this form by rotation of the roller to the surface of a charged electrophotographic material which has been exposed imagewise and is traversed over the roller. The toner is attracted electrostatically from the magnet to the photoconductive coating of the electrophotographic material and a visible image is formed.
U.S. Pat. No. 4,111,546 to Maret which discloses an electrostatographic reproducing apparatus and process that includes a system for ultrasonically cleaning residual material from the imaging surface. Ultrasonic vibratory energy is applied to the air space adjacent the imaging surface to excite the air molecules for dislodging the residual material from the imaging surface. Preferably pneumatic cleaning is employed simultaneously with the ultrasonic cleaning. Alternatively, a conventional mechanical cleaning system is augmented by localized vibration of the imaging surface at the cleaning station which are provided from behind the imaging surface.
Xerox Disclosure Journal, volume 18, no.3, May/Jun. 1993, entitled "Acoustical Vacuum Cleaner Assist" discloses a high velocity and pressure vacuum that subsequently removes particles from the photoreceptor belt. The particles being previously dislodged by the vibratory action of an acoustical horn against the photoreceptor belt.